Antihalation layer



March 30, 1937.

ANTIHALATION LAYER Filed Dec. l, 1932 eff/P10007' WW- dgm w. SCHNEIDER 2,075,145

Patented4 Mar. 30, 1931 .UNITED STATES f PATENT OFFICE 1 y "2,015,145 f E r e MANTIHALATION'LAYEB wilhelm schneider, Dessau in'anhalt, Germany,

assignor to Agfa Ansco Corporation, Binghamton, N. Y., a corporation ofNew York Application December 1, 1932, Serial No. 645,310

In Germany December 15, 1931 5 Claims. (01.'95-8l My present invention relates to anti-halation layers for photographic plates and lms, and more particularly to an anti-halation layer applied on the rear side of such plates and lms.

5 One of its objects is to provide a process-.of

preventing particles to split from the colored layer b y coating the said layer with a protecting layer of natural or artificial resin containing at least one hydroxyl group or carboxyl group capable of forming a. salt. Another object is the plates and' lms provided with an improved anti-hala# tion layer. Further objects will be seen from the detailedspeciflcation following hereafter.

In my co-pending application Serial Number 569,067 -filed October 15, 1931, I have described a process of protecting an anti-halation layer ap plied on the rear s ide of a photographic plate or film by coating the anti-halation layer with a thin layer of a diarylmethane derivative containing at least one hydroxyl group or carboxyl group in its molecule.

' According to my present invention I have found that most valuableprotecting layers are obtainable by the application of natural or artificial resins containing intheir molecule a hydroxyl group or a carboxyl group capable of forming a salt. 'I'hese layers are soluble in alkaline baths such as the developers, feebly alkaline solutions being capable of dissolving the protecting jlayer if the resin containsa carboxyl group. Valuable products for the purpose in view are also obtained by treating natural resins with alkali and precipitating the said products by means of an acid.A

As suitable artificial resins I enumerate, for

instance, the condensation products of formaldehyde or a substance splitting off formaldehyde or phenolalcohol with a phenol, phenylalkylether, phenylarylether, oxycarboxylic acid, an alkyloxycarboxylic acid or phenoxy fatty acid, furthermore an artic'ial resin which has been treated with a halogenated fatty acid, or a product 0btained by condensing a phenol or a phenolcarvboxylic acid with an aliphatic, aromatic or heterocyclic aldehyde or with thionyl chloride. The

formation of these products is known (cf. for instance DRP. 364,040; 371,148; 391,539; 439,962; 449,276; 363,383; 358,401; 357,757; 339,495; 357,758) and is not claimed in this invention. Natural resins which by a treatment with alkali become suitable for my invention are, for instance, shellac and colophony.

. The protective coating is produced by applyingto the anti-halation layer a non-aqueous solution of the resin and generally has a thickness of about 0.5 to 2p. It completely protects the antihalation layer from mechanical damage in the camera and from being impaired by the aqueous vapor containedin the air. Consequently, colored particles cannot stain Ythe emulsion layer nor deposit in the-exposure gate off-the camera. 5

The following examples illustrate'the inven- 'tion Example 1.-A solution of 50 grams of ammonium polyglucuronate, 50 grams of methyl blue 'in 5000 cc. of water is applied on the Iback of an 10 acetylcellulose or nitrocellulose lm in a thick# ness of 1-2p.. After drying.' the anti-halation layer thus obtained i s coated with a solution of 250 grams of artificial resin, prepared from phenoxyacetic acid and formaldehyde, in 5000 cc. of 15 alcohol. 'I'he coating dissolves even in very weak alkaline. developers within about 10 to 20 seconds.

.Y .by means of a solution of 50 grams of methyl 25 blu'e in 2500 cc. of water and 2500 cc. of alcohol.

After drying, the anti-halation layer isv coated with a solution of 250 grams of .colophony in 5000 c'c. of butanol. The colophony was rst dissolved in sodium'carbonate and precipitated from this 30 solution by addition of diluted hydrochlorid acid. The coating dissolves within a yshort time in` strong alkaline developers.

Example 4.-To the same lm as inv Example 3 there is applied on the .anti-halation layer a 35 protective layer from a solution of 250 grams of the condensationproduct of ortho-methoxy-benzoic acid with p-cresol-di-alcohol in 5000 cc. of propanol.

My invention is not limited to the foregoing 40 examples or to the specific details given therein. The solvent for the solutions of the resin and its concentration are adapted to the requirements and can be easily determined by a few simple experiments. The hydroxyl group or carboxyl 45 group can be positioned in the aliphatic radical 'or in the aromatic radical of the resins. Numerous other embodiments are possible and I contemplate to be within the spirit of my invention all such modifications and equivalents as fall 50 within the scope of the appended claims.

The annexed drawing illustrates my invention. The gure represents a sectional view of a photographic plate prepared according to my invention.` In this ligure, l is the glass plate which 55 serves as support, 2 is the emulsion layer, l is the color layer forming the anti-halation layer on the back of the plate, and 4 is my new coating layer preventing particles of being split oi! from 5 the colored layer.'

1. Photographic plates or iilms comprising a support bearing on one side a light-sensitive emulsion layer and on the other side a solid antilQ halation layer coated with a protective layer containing a resin easily soluble in alkaline developers containing at least one radical capable of forming a, salt selected from the group consisting emulsion layer and on the other side an'anti halation layer coated with a. protective layer con- 25 taining an alkali-soluble phenol-acetaldehyde resin.

4. `Photographic plates or nlms comprising a :,omus

support, bearing'on one side a iight sensitive emulsion layer and on the other side an antiv phenylcarboxylicy acid resins, formadehydephenoxy fatty acid resins, phenoiaicohol-phenylalkyl ether resins, phenolalcohol-phenylaryiether resins, phenol-alcohol-oxyphenylcarboxylic acid resins, phenolaloohol-alkoxyphenylcarboxylic acid resins, phenolalcohoi-phenoxy fatty acid resins, phenol-aliphatic aldehyde resins, phenol-aromatic aldehyde resins, phenol-heterocyclic aldehyde resins, phenol-thionyl chloride resins, phenol-carboxylic'acid-aromatic aldehyde resins, phenolcarboxylic acid-heterocyclic aldehyde resins and phenolcarboxylic acid-thionvichloride resins.

WILHELM SCHNEIDER. 

